1. Field of Invention
The present invention relates to a liquid crystal driving circuit and a liquid crystal display device including the same, in particular, a liquid crystal partial driving circuit configured by a TFT (Thin film transistor) gate driver made of amorphous silicon and capable of performing partial drive in standby, and a liquid crystal display device including the liquid crystal partial driving circuit.
2. Related Art
The liquid crystal display device has relatively small power consumption. But recently, further reduction in power consumption is desired particularly in the field of portable telephones and the like as a result of demand for extended operation. For example, further reduction in the power consumption is desired even in the reflection type liquid crystal display device although the reflection type liquid crystal display device originally does not use a backlight and has small power consumption.
A liquid crystal driving circuit employing a shift transistor is known to reduce power consumption and to reduce the wiring space of the liquid crystal display device to enhance space efficiency. In the liquid crystal display device, the display row is sequentially selected by the shift register, and the TFT is driven for the liquid crystal to perform the display.
Such selective drive is performed only when a signal from a previous line is input to the relevant line, and high impedance is realized using a capacitor is disclosed in U.S. Pat. No. 6,064,713. In U.S. Pat. No. 6,064,713, a bootstrap technique is also used to obtain sufficient driving voltage.
A partial drive method is proposed and put to practical use to further cut down the power by performing the display not on the entire liquid crystal display elements, but only on one part during standby.
In the partial driving method, advancement is made to the line to display, a switch arranged on the line to be selectively driven is turned ON, and the scan data is provided to the TFT.